Present a RAID1 (2 SSDs) to the Installer or Select both SSDs during Install?

[theprez]

Which is the best practice for installation?

Configuring software raid1 (from the BIOS) on the two SSDs used for installation (the dataset drives are on a HBA IT mode) and have it presented to the installer as 1 drive or leave it as AHCI in the BIOS, two drives presented to the OS and select both during the install so they can be mirrored?

Said differently, is it best to have the software RAID1 handle the mirroring of both SSDs or disable that, use AHCI, select both disks during install and have TrueNAS manage the mirroring of the SSDs?

Thanks

 

[Alecmascot]

Always best to let TrueNAS handle the disks directly.
Disable the Bios Raid.

 

[sretalla]

Said differently, is it best to have the software RAID1 handle the mirroring of both SSDs or disable that, use AHCI, select both disks during install and have TrueNAS manage the mirroring of the SSDs?

It depends...

Some BIOS/RAID will handle the boot process better, meaning if there's a disk lost and a reboot happens, you'll always boot to the remaining mirror member with one lost. Assuming you're looking for a system that requires no intervention in order to reboot even with a failed boot drive, maybe that's best.

What you won't get with that is ZFS protection against file corruption... you'll be able to use checksums to detect problems, but won't be able to auto-correct them with scrubs. Maybe not important to you if you back up your config regularly outside the boot pool.

Using ZFS mirrors, you'll get the ability to survive a drive failure and continue running, but may not be able to boot without intervention. Obviously as already stated, that gives you the full ZFS protection, but doesn't cover the hardware/BIOS boot process.

Make your assessment on what you're looking to solve with mirrored boot drives and plan accordingly.

 

[EnKo]

If I understand your question right, you actually want to decide between hardware RAID and software RAID. I personally decided for software RAID in order to be independent from hardware suppliers. It is very likely in case of hardware fail after many years of running, you are not able to find a compatible replacement. In worst case this ends in a total loss of data. While a software RAID can be read practically by any hardware. When I setup my first FreeNAS I intensively tested the software RAID functions and was completely satisfied.